Laryngoscope blade

ABSTRACT

A laryngoscope blade which improves the transmission of light from the laryngoscope to enhance the amount of light reflected from an area of interest in a patient. The laryngoscope blade has a channel which extends at least partially though the blade and receives a light source. The channel has a substantially transparent end face which is situated towards the blade end and has an optical clement adapted to reduce the ambient light signal from the light source in the channel.

This application is a continuation of U.S. patent application Ser. No.14/753,835 filed Jun. 29, 2015, which is a continuation of U.S. patentapplication Ser. No. 12/086,245, filed Jun. 9, 2008, which is a U.S.national phase of International Application No. PCT/GB2006/004608 filedDec. 11, 2006, which designated the U.S. and claims priority to BritishPatent Application Nos. 0525095.6 filed Dec. 9, 2005 and 0525085.7 filedDec. 9, 2005, the entire contents of each of which are herebyincorporated by reference.

The present invention relates to sheath type laryngoscopes and inparticular to blades including disposable blades for said laryngoscopes.

The laryngoscope is a device that is used by physicians to open-up apatient's airway during the intubation process. One key aspect of theuse of a laryngoscope is that the physician must be able to identify thevocal cords and surrounding anatomy when the laryngoscope is inserted.In most cases, this is done by visual identification of the larynx areaby looking directly into the patient's mouth or by viewing that area ona video screen by having a camera positioned on, or within, thelaryngoscope blade.

In general it is known to fit a light source to the outside of a nondisposable laryngoscope blade. In addition some disposable laryngoscopeblades consist of a sheath type blade with a transparent section thatallows transmission of light from an end face into the throat of thepatient. The light is intended to illuminate the anatomy so that a mediccan see, or for an imaging system to capture an image. The advantage ofa sheath is that the imaging and/or light source is protected fromcontact with the patient and is therefore better protected from patientto patient cross infection. Another advantage is that the relativelyexpensive camera and/or light source forms part of the reusable portionof the device, keeping the disposable sheath portion free fromelectronics and precious metals, which enables a cost effective andenvironmentally friendly solution.

One problem with the use of light sources mounted inside a sheath-typelaryngoscope blade is that the light must transfer through thesubstantially transparent end face of the blade (or sheath) and can bereflected or otherwise leak into the sheath to cause a polluting ambientlight signal, or scattering light. In addition, the scattered lightmeans that not all of the light from the light source reaches theintended area in the patient's throat to provide a useful signal.

The problem is made worse by using light sources which provide a widefield of light that spreads to a wider area than the intended area ofillumination. The wide angle causes the light to spread into the sheathinstead of travelling through the sheath directly and efficiently.Additionally, the amount of light reaching the desired target area isdiluted. A narrow beam of light will travel through the sheath windowefficiently, with less scattering, but will often not allow a wideenough field of illumination on the target area.

A related problem with the illumination of the internal anatomy for thepurpose of imaging for viewing on an external monitor is that the lightsource creates a circular field of illumination, like a cone of light,which is not optimal for current monitors which are rectangular ratherthan circular. Current systems therefore offer a circular spot of lightwithin the frame of the monitor, or illuminate a wider circle of lightbeyond the frame of the monitor, which means light is wastedilluminating anatomy that is not displayed on the viewing monitor.

Medical probes for internal examination of the anatomy, such aslaryngoscope blades, are often used alongside additional apparatus alsoinserted into the body. In the case of a laryngoscope blade a trachealtube is passed into the patient's airway through the vocal cords. Thismeans that it is preferable to have the laryngoscope blade positioned toone side (usually the left) to provide a space for the tube to beinserted. This means that the image capture and/or illumination meansare offset to the target area, and therefore must be angled to thetarget area which can add complexity, cost and often results in bulkierpackaging.

It is an object of the present invention to improve the operation of alaryngoscope by improving the transmission of light from thelaryngoscope to enhance the amount of light reflected from an area ofinterest in a patient.

In accordance with the first aspect of the present invention there isprovided a laryngoscope blade for a sheath type laryngoscope, the bladecomprising:

a hilt;

a blade end; and

a channel extending at least partially though the blade and beingadapted to receive a light source, the channel having a substantiallytransparent end face situated towards the blade end and the end facecomprising an optical element adapted to reduce the ambient light signalfrom the light source in the channel.

The blade end is the distal end with respect to the hilt. Also, theambient light signal includes any scattered light.

Preferably, the blade further comprises an opening. Advantageously theopening is located at or near the hilt.

Preferably, the optical element is shaped to reduce the back scatter oflight into the channel.

Preferably, the end face contains a castellation such that the positionof the end face from which the light is emitted is in front of theremainder of the end face.

Preferably, the optical element is bounded at least in part by achannel.

Preferably, the optical element is adapted to redirect the beam oflight.

Preferably, the optical element is adapted to spread the beam of light.Alternatively, the optical element is adapted to focus the beam oflight.

Preferably, the optical element comprises a refractive means.

Preferably, and advantageously, the optical element is adapted to shapethe beam of light so as to have a substantially rectangular crosssection.

Optionally, the optical element comprises a prism.

Preferably, the optical element is adapted to receive a narrow beam oflight and to broaden out the beam.

Preferably, the optical element further comprises a lens.

Optionally, the lens is a concave lens.

Optionally, the lens is a convex lens.

Preferably, the optical element is adapted to absorb light incident uponits side face.

Optionally, the optical element is adapted to reflect light incident onits side face.

Preferably, the channel is further adapted to receive a camera.

Preferably, the channel is adapted to receive a fibre optic or L.E.Dlight source.

Preferably, the light source emits light from a position at or near thetransparent end face.

The present invention will now be described by way of example only withreference to the accompanying drawings in which:

FIG. 1 is a perspective view of a first embodiment of the presentinvention;

FIG. 2 is a cross-sectional view of the embodiment of FIG. 1 ;

FIG. 3 is a cross-sectional view of the end face area of a secondembodiment of the present invention;

FIG. 4 is a cross-sectional view of the end face area of a thirdembodiment of the present invention;

FIG. 5 is a cross-sectional view of the end face area of a fourthembodiment of the present invention;

FIG. 6 is a cross-sectional view of the end face area of a fifthembodiment of the present invention;

FIGS. 7 a to 7 e are cross-sectional views of the alternative end facesof the embodiment of FIG. 1 ;

FIGS. 8 a to 8 c illustrate a light source or image capture device andvarious optical elements thereof;

FIGS. 9 a to 9 f illustrate an alternative light source or image capturedevice, various optical elements thereof, and the effects of the opticalelements; and

FIGS. 10 a and 10 b illustrate cross-sectional views of embodiments ofthe present invention incorporating the optical elements.

FIG. 1 shows a blade 1 comprising an opening 2 and a hilt 3 havingcoupling means 4 for connecting the sheath type blade 1 to alaryngoscope, a blade end 5 having a blade tip 6.

The blade 1 contains a channel 9 which extends from the hilt 3 to theend face 7. The end face supports 10 are provided either side of the endface to improve the structural strength of the blade. The channel 9 issuitable for insertion of an image capture and/or an illuminationdevice.

FIG. 2 is a cross-sectional view of the end face 7. The end facecontains an optical element 11 adapted to receive light from a lightsource 17. The optical element 11 comprises a prism 15 and is bounded bya gap or channel 13 which separates the optical element 9 from a secondoptical element 12 adapted to receive reflected light from the throatarea (or other area of interest) of a patient and to transmit this lightto a camera 19.

In this example of the present invention prisms 14 and 15 producedifferent degrees of refraction as a result of their different shapes.

In use, the first embodiment of the present invention is provided with alight source 17 and a camera 19. The light source 17 and camera 19 areinserted into the channel 9 and positioned at or near the end face 7.When a laryngoscope containing a sheath blade 1 as shown in FIG. 1 is inuse, the light source 17 and camera 19 are switched on such that lightmay be transmitted down the throat of the patient for the reflectedlight to provide a signal which can display on a screen the area inwhich the laryngoscope blade is situated. This allows the physician tomore accurately position the laryngoscope.

By modifying the end face 7, the present invention reduces the amount oflight from the light source that leaks directly into the camera (ambientlight) and increases the amount of light that is reflected from thethroat area of the patient. In addition, the prisms 15 and 14 correctthe direction of the transmitted and received light signals.

In this example the small degree of castellation is used to position thearea from Which the light is omitted from the end face 7 in front of thearea where reflected light is received by the camera 19. In addition,the optical element 11 is bounded by a gap or channel 13 which reducesthe level of transmission of light across the front of the camera.

FIG. 3 shows a second, embodiment of the present invention in which theend face 21 comprises a castellation 23, a narrow light source 27 and acamera 19. In this example, the narrow light source 27 is provided alongwith an optical element 25 comprising a lens 26 which causes the narrowbeam to diverge and which maximises the amount of light that is incidentupon the area of interest within the patient.

The combination of having the light source situated in front of thecamera 19 and the use of a light source which provides a thin or narrowbeam of light reduces the amount of ambient or back scattered lightincident on the camera and increases the amount of reflected lightincident upon the camera 19.

FIG. 4 shows a third embodiment of the present invention in which theend face 31 comprises a castellated section 33 which, in this example,has the light source set in front of the remainder of the end face butsubstantially in the centre of the end phase. In this example of thepresent invention a camera is not present.

This embodiment of the present invention is designed to allow the directvisual inspection of the area of interest in the patient without the useof a camera. It has been found that the problem of ambient and/orbackscattered light is important when a physician is attempting todirectly observe the position of a laryngoscope blade as the ambientlight makes it more difficult to correctly identify parts of the throatand voice box. By offsetting the position of the light source in frontof the remainder of the end face 31, the level of ambient light that hisviewed by the physician is reduced and the view improved.

FIG. 5 shows a fourth embodiment of the present invention in which theend face 41 is substantially flat except for the presence of an opticalelement 45. The end face is provided with the light absorbing barrier 43which prevents light from the light source from entering the channel 9.The optical element 45 is positioned in front of the light source and isused to bend and/or expand the beam on exit from the end face 41.

In a further embodiment of the present invention the absorbing barrier43 may be replaced by a barrier that reflects light internally such thatlight is not transmitted into the channel but reflected back toward theend face for transmission into the patient.

FIG. 6 shows another embodiment of the present invention in which theend face 51 is provided with a channel or gap 53, a converging lens 55positioned in front of the light source 61, and a camera prismpositioned in front of the camera 19.

In this example of the present invention, the level of ambient orscattered light that effects the signal received by the camera 19 isproduced by using a converging lens that focuses the light to a point 60beyond the end face 51 with the beam subsequently diverging to maximisethe amount of light incident upon the area of interest in the patient.

It will be noted that the curvature of the lens and therefore the degreeof convergence or divergence that is required will be assessed on thebasis of the distance between the end face 51 and the blade tip 6 (FIG.1 ) along with the estimated distance from the blade tip 6 to the voicebox of a patient.

FIGS. 7 a to 7 e show cross-sectional views of alternative end faces 107(corresponding to end face 7 in FIG. 1 ). The end face contains anoptical element 111 adapted to receive and transmit light from a lightsource 121. The optical element 111 is separated into two parts toprevent light from the light source 121 scattering through the end face107.

In FIG. 7 a the separation is achieved by a castellation feature 111which positions the light source 121 in front of the image capturedevice. In FIG. 7 b the separation is achieved by separator element 112,whereas in FIG. 7 c the separation is achieved by an air gap separation113.

In FIG. 7 d and FIG. 7 e the separation is achieved by a combination ofthe castellation feature 111 and either the separator element 112 or theair gap separator 113, respectively.

FIG. 8 a and FIG. 8 b illustrate a light source or image capture device119 configured to transmit or receive light through an optical element118. In FIG. 8 a , the natural beam of light 114 transmitted or receivedis narrower than an optimal beam 115 as required to illuminate a target120. In FIG. 8 a , the natural beam of light 116 transmitted or receivedis wider than the optimal beam 115. In FIG. 8 a , substantial areas ofthe target 120 are not illuminated or imaged. In FIG. 8 b , theillumination or imaging of the target 120 is inefficient as asubstantial amount of the illumination or image falls outwith the target120.

In order to achieve the optimal beam 115, the shape and size of the beamof light 114,116 transmitted to or received from the target 120 can bemanipulated by the optical element 118 which may take the form of one ofthe lenses illustrated by FIG. 8 c . These lenses may cause the beam oflight to tend to converge or diverge towards the optimal beam 115.

FIG. 9 a and FIG. 9 b illustrate an alternative light source or imagecapture device 119 configured to transmit or receive light through anoptical element 118. In this case the target 120 is offset from thelight source or image capture device 119.

In FIG. 9 a , the natural beam of light 114 transmitted or received isnarrower than the optimal beam 117 as required by the offset target 120.In FIG. 9 b , the natural beam of light 116 transmitted or received iswider than the optimal beam required by the offset target 120.

In order to achieve the optimal beam 117, the shape and size, of thebeam of light 114,116 transmitted to or received from the offset target120 can be manipulated by the optical element 118 which may take theform of a prism or a combined prism and lens such as those illustratedby FIG. 9 c.

FIG. 9 d illustrates the effect of the narrow natural beam 114 withrespect to the offset target 120, and FIG. 9 e illustrates the effect ofthe wide natural beam 116 with respect to the offset target 120.Substantial areas of the offset target 120 are not illuminated or imagedby the narrow natural beam 114, and importantly a significant area ofthe centre of the offset target are not illuminated or imaged. Theillumination or imaging of the target 120 by the wider natural beam 116is inefficient as a substantial amount of the illumination or imagefalls outwith the offset target 120, nevertheless, a significant area ofthe offset target is not illuminated or imaged.

FIG. 9 f illustrates the result of correction of the natural beam114,116 using an optical element 118 which may be selected from thoseillustrated in FIG. 9 c or a combination thereof. The shaping of thenatural beam 114,116 is such that a substantially rectangular shape isachieved, resulting in a more efficient use of light.

FIG. 10 a and FIG. 10 b illustrate cross-sectional views of the end faceof embodiments of the present invention incorporating optical elementsfor improved imaging of an offset target 120.

A light source 121 and an image capture device 122 are inserted into thechannel 109 which leads to the end face 107. The end face 107 comprisestwo separate optical elements, one for light transmission 123 and onefor image capture 124. The optical elements 123,124 are separated by acastellation feature 111 which prevents scattering of light from thelight source 121 into the image capture device 122.

The optical element for image capture 124 takes the form of a prism tocollect light from the offset target 120. The optical element for thelight source 123 takes the form of a lens and a prism to manipulate theshape and size of the light field 125 and direct it to the offset target120. In FIG. 10 b , the optical elements 123,124 are further separatedby an air gap separator, further reducing any scatter from the lightsource 121 to the image capture device 122.

The present invention provides improvements in and relating to sheathtype laryngoscopes by reducing the amount of scattered or ambient lightthat is received by a camera or directly received by the physician whenviewing an area of interest in a patient. The present invention alsoassists with the correction of the beam direction and shape.

A preferred embodiment spaces apart the light source and the imagecapture means by way of a light stopping barrier and/or a castellationat the window area of the sheath. In the present invention the directionand shape of the illumination coming from the light source within thesheath is corrected so as to illuminate the desired area of the anatomy.In a preferred embodiment this is achieved by way of a prism and anangled lens which project a rectangular beam of light, at an angle, tosuit that of the image capture means or display monitor.

Improvements and modifications may be incorporated herein withoutdeviating from the scope of the invention as defined by the appendedclaims.

What is claimed is:
 1. A laryngoscope blade comprising: a sheath forminga channel extending at least partially through the laryngoscope bladeand configured to receive a light source and a camera and wherein thesheath is configured to cover the light source and the camera such that,in use, the light source and the camera are protected from contact witha patient, the channel having an opening disposed adjacent to a proximalend of the blade and terminating in an external end cap through whichlight from the light source is transmitted, wherein the external end capcomprises a prism producing a degree of refraction such that the throatarea in which the blade is situated is visible to the camera, whereinthe external end cap comprises a stepped interior surface wherein theprism is disposed within a first step of the stepped interior surfacethat is distal to a second step through which the camera is configuredto receive the light; an elongated surface extending distally andlaterally away from the external end cap to form a blade tip, whereinthe blade tip is separated from the external end cap by the elongatedsurface; and end face supports extend from the external end cap to theelongated surface to provide strength to the laryngoscope blade.
 2. Thelaryngoscope blade of claim 1, wherein the prism is configured to focusthe light on a point positioned between the blade tip and the externalend cap.
 3. The laryngoscope blade of claim 1, wherein the prism isconfigured to redirect a beam of the light towards an offset targetoffset from an axis of the channel.
 4. The laryngoscope blade of claim1, wherein the prism is configured to redirect a beam of the lighttoward a wall or surface of the blade tip or towards a target positionedpast the blade tip.
 5. The laryngoscope blade of claim 1, wherein theexternal end cap is at least partially transparent.
 6. The laryngoscopeblade of claim 1, wherein the stepped interior surface comprises adistal portion and a proximal portion, and wherein the prism is in thedistal portion.
 7. The laryngoscope blade of claim 1, wherein anexterior surface of the external end cap is coupled to a side wall ofthe laryngoscope blade, wherein the side wall extends from a distal endof the channel toward the blade tip along at least a portion of theelongated surface, and wherein the side wall is orthogonal to theelongated surface.
 8. The laryngoscope blade of claim 1, wherein thestepped interior surface opposes an exterior surface of the external endcap, wherein the exterior surface is not stepped.
 9. The laryngoscopeblade of claim 8, wherein the exterior surface is a planar surfaceextending between opposing side walls of the channel.
 10. Thelaryngoscope blade of claim 1, wherein the stepped interior surfacecomprises a distal portion and a proximal portion, and wherein theproximal portion is longer than the distal portion across across-section of the channel.
 11. The laryngoscope blade of claim 1,wherein the external end cap is transparent along the stepped interiorsurface.
 12. The laryngoscope blade of claim 1, wherein the elongatedsurface extends from an inner curve of the channel.
 13. The laryngoscopeblade of claim 1, wherein the blade tip is wider than the channel.
 14. Alaryngoscope comprising: a laryngoscope body; a light source and acamera coupled to the laryngoscope body; and a laryngoscope bladecoupled to the laryngoscope body, the laryngoscope blade forming achannel extending at least partially through the blade and configured toreceive the light source and the camera, the channel terminating in anexternal end cap extending between side walls of the channel to closethe channel at one end and through which light from the light source istransmitted, wherein the external end cap comprises a stepped interiorsurface, and wherein the external end cap is configured to direct lightfrom the light source, and wherein the laryngoscope blade comprises anelongated surface extending longitudinally and laterally away from theexternal end cap to form a blade tip; and end face supports extend fromthe external end cap to the elongated surface to provide strength to thelaryngoscope blade.
 15. The laryngoscope of claim 14, wherein theexternal end cap comprises a prism.
 16. The laryngoscope of claim 15,wherein the prism is configured to focus the light on a point positionedbetween the blade tip and the external end cap.
 17. The laryngoscope ofclaim 15, wherein the prism is configured to redirect a beam of thelight towards an offset target offset from an axis of the channel. 18.The laryngoscope of claim 15, wherein the prism is configured toredirect a beam of the light toward a wall or surface of the blade tip.19. The laryngoscope of claim 15, wherein the prism is configured tobend, expand, or redirect a beam of the light towards a targetpositioned past the blade tip.
 20. The laryngoscope blade of claim 14,wherein an exterior surface of the external end cap is coupled to a sidewall of the laryngoscope blade, wherein the side wall extends from adistal end of the channel toward the blade tip along at least a portionof the elongated surface, and wherein the side wall is orthogonal to theelongated surface.
 21. The laryngoscope of claim 14, wherein the steppedinterior surface is configured to transmit light from the light sourcethrough a first step and direct received light to the camera through asecond step.
 22. The laryngoscope of claim 14, wherein the elongatedsurface extends laterally away from the channel proximal of the externalend cap.